Teach two-address pass to update the "source" map so it doesn't perform a

non-profitable commute using outdated info. The test case would still fail
because of poor pre-RA schedule. That will be fixed by MI scheduler.

rdar://11472010

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157038 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index e299671b68bb17f8af5382ede9b8635f60f6d8f8..8164690e40abc082f2cfa3f6504d442a06df26aa 100644 (file)
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -1521,6 +1521,7 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
 #endif
 
           // Emit a copy or rematerialize the definition.
+          bool isCopy = false;
           const TargetRegisterClass *rc = MRI->getRegClass(regB);
           MachineInstr *DefMI = MRI->getVRegDef(regB);
           // If it's safe and profitable, remat the definition instead of
@@ -1537,10 +1538,11 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
           } else {
             BuildMI(*mbbi, mi, mi->getDebugLoc(), TII->get(TargetOpcode::COPY),
                     regA).addReg(regB);
+            isCopy = true;
           }
 
-          MachineBasicBlock::iterator prevMI = prior(mi);
           // Update DistanceMap.
+          MachineBasicBlock::iterator prevMI = prior(mi);
           DistanceMap.insert(std::make_pair(prevMI, Dist));
           DistanceMap[mi] = ++Dist;
 
@@ -1554,6 +1556,10 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
             RemovedKillFlag = true;
           }
           MO.setReg(regA);
+
+          if (isCopy)
+            // Propagate SrcRegMap.
+            SrcRegMap[regA] = regB;
         }
 
         if (AllUsesCopied) {

diff --git a/test/CodeGen/X86/2012-05-17-TwoAddressBug.ll b/test/CodeGen/X86/2012-05-17-TwoAddressBug.ll
new file mode 100644 (file)
index 0000000..171c3f1
--- /dev/null
+++ b/test/CodeGen/X86/2012-05-17-TwoAddressBug.ll
@@ -0,0 +1,16 @@
+; RUN: llc < %s -mtriple=x86_64-apple-macosx -pre-RA-sched=source | FileCheck %s
+
+; Teach two-address pass to update the "source" map so it doesn't perform a
+; non-profitable commute using outdated info. The test case would still fail
+; because of poor pre-RA schedule. That will be fixed by MI scheduler.
+; rdar://11472010
+define i32 @t(i32 %mask) nounwind readnone ssp {
+entry:
+; CHECK: t:
+; CHECK-NOT: mov
+  %sub = add i32 %mask, -65535
+  %shr = lshr i32 %sub, 23
+  %and = and i32 %mask, 1
+  %add = add i32 %shr, %and
+  ret i32 %add
+}